1. Field of the Invention
The present invention relates to a metal oxide nano powder and manufacturing method of the same, and more particularly, to a nano-sized metal oxide and manufacturing method of the same which has a relatively large specific surface area, is economical to manufacture, and exhibits excellent chemical activity.
2. Description of Related Art
In general, a zinc oxide is used for a photocatalytic, a diluted magnetic semiconductor, and the like. Also, a zinc oxide is widely used as a fluorescent pigment and a material for a light emitting diode (LED). A copper (I) oxide (Cu2O) is a p-type semiconductor material and used for a rectifier filter, which is operated using ionization property, together with copper of a transition metal. Also, Cu2O functioning to emit electrons in a photo-cell is used for a material of a photo-cell, a pigment for preventing corrosion, a cathode for a lithium-ion battery, and a catalyst for conversion of a solar energy.
A zinc oxide and a copper (II) oxide (CuO) are manufactured by heating a zinc metal and a copper metal in air. Cu2O may be manufactured by adding hydrazine to a copper (II) acetate solution, by heating a Fehling's solution with glucose added or by performing a chemical reaction using copper hydroxide (Cu(OH)2).
However, conventional methods for manufacturing metal oxide powder as described above are unsuitable for a large-quantity production process due to cost increase and complexity in the manufacturing process. Specifically, the above-mentioned conventional manufacturing methods are suitable for manufacturing a metal oxide powder having a particle size greater than or equal to a micron sized particle. However, the conventional manufacturing method is unsuitable for manufacturing a metal oxide powder having nano-sized particles or having specific shaped particles transformed to a bar-form or a wire-form. Also, a zinc oxide doped with a metal is difficult to be manufactured through the conventional manufacturing methods due to a significantly low melting point and boiling point of zinc.
Generally, since alumina has high thermal resistance, chemical resistance, corrosion resistance, and high strength, it is used, often in a fiber form, as a catalyst for decomposition of organic matters related to environmental pollution, a high functional filter, and a reinforcement agent for composite materials, and also used in the formation of gas separation membranes. An iron oxide having high thermal resistance, chemical resistance, corrosion resistance, and high strength is mainly classified into hematite (α-Fe2O3) and maghemite (γ-Fe2O3) which are used as a catalyst for a magnetic recording media and petrochemistry due to magnetic properties, and ferrite-based magnetite (Fe3O4), which is applied to a magnetic toner and a drug delivery medium. These iron oxides advantageously have large-energy products, reduced costs of materials, reduced material instability, reduced weight of materials, and exhibit corrosion resistance. Also, these iron oxides are manufactured in a bar-form, a fiber-form, and a wire-form, and thus, applicably used for magnetic materials, printing recording materials, bio-materials, and the like. As methods for manufacturing an alumina fiber or an iron oxide bar described above, a melt spinning method, a sol-gel method, an extrusion method, and the like, are widely used.
The sol-gel method refers to as a method using a phenomenon in which a chain reaction occurring by an alcohol oxide is maintained in a solution, that is, ‘sol’, where colloidal particles, inorganic particles, and solid particles are dispersed so that the dispersed solid materials are polymerized, and thereby a fluid gel having a consecutive solid retina structure is obtained.
However, conventional fiber manufacturing methods such as the sol-gel method, the melt spinning method, and the extrusion method have problems in that the manufacturing process is complex, and the manufacturing costs are increased. In addition, because alumina fibers and iron oxide bars manufactured by the conventional fiber manufacturing methods have micrometer or sub-micrometer particle sizes, the alumina fiber and iron oxide bars do not advantageously increase in the specific surface areas compared with the nano-sized particles nor increase in the mechanical property value.
Currently, manufacturing methods of powdering various kinds of metals such as aluminum, iron, copper, and zinc in order to get nano-sized particles have been developed. This is because when a metal is powdered to have nano-sized particles, mechanical properties such as hardness, strength, abrasion resistance are improved, and physical properties such as chemical and electromagnetic properties are improved, showing an increase in the thermal expansion coefficient, a reduction in activation energy, and the like, in comparison with the existing materials.
Also, when a zinc oxide or a zinc oxide doped with transition metals such as aluminum, iron, and the like, is manufactured in a bar-form having a particle size of several to tens of nano-meters, the mechanical property value is improved, and a range of the application is expanded due to fine constituting particles of the zinc oxide.
However, conventional manufacturing methods for metal oxide have a shortcoming in that a particle of a nano-sized metal oxide is difficult to be shaped. Also, a conventional composite method of a nano-sized inorganic crystal is difficult to be applied to manufacturing methods of a nano-sized metal oxide having a nano sized bar-form, a nano sized cube-form, or a nano sized fiber-form due to the disadvantages described above. Therefore, there is a need for a manufacturing method of a nano sized metal oxide which is simple, economical, and effective in the manufacturing process.